Generic Limits of Pyrinae: Insights from Nuclear Ribosomal DNA Sequences
The subtribe Pyrinae, formerly the Maloideae, is a monophyletic group of about 1,000 species that includes well known fruit crops such as apple (Malus), pear (Pyrus), quince (Cydonia), loquat (Eriobotrya), chokeberry (Aronia), and serviceberry (Amelanchier). Generic limits have been fluid in Pyrinae, especially in Malus, Sorbus and Photinia. This study evaluated the generic limits of 180 samples of multiple species or accessions from each of the traditional genera using sequences of the nrDNA ITS region. The ITS data recognized 24 genera, including Amelanchier, Aria (including Micromeles), Aronia, Chaenomeles, Chamaemespilus, Chamaemeles, Cormus, Cotoneaster, Crataegus, Cydonia, Dichotomanthes, Eriobouya, Hesperomeles, Malacomeles, Malus (including Chloromeles, Docynia, Docyniopsis, and Eriolobus), Mespilus, Osteomeles, Peraphyllum, Pourthiaea, Pseudocydonia, Pyrus, Rhaphiolepis, Sorbus, and Torminalis. However, both Photinia and Pyracantha are polyphyletic. Photinia is separated into different clades, one of which contains species of Heteromeles and Stranvaesia. Asian species of Pyracantha do not form a clade with P coccinea of southern Europe and Iran. Our results support the close relationship of Amelanchier, Malacomeles, and Peraphyllum, and of Crataegus and Mespilus, and for the first time recognize the sister relationship of the South American genus Hesperomeles with the Crataegus-Mespilus clade.